Functional in vitro test of calmodulin antagonism: effect of drugs on interaction between calmodulin and glycolytic enzymes

• Published in: Molecular pharmacology Vol. 33; no. 6; pp. 678 - 682
• Main Authors: OROSZ, F, CHRISTOVA, T. Y, OVADI, J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Pharmacology and Experimental Therapeutics 01.06.1988
• Subjects: Antianginal agents. Coronary vasodilator agents; Biological and medical sciences; Calcium Channel Blockers - pharmacology; calmodulin; Calmodulin - antagonists & inhibitors; Calmodulin - metabolism; Cardiovascular system; Fendiline - pharmacology; fructose-bisphosphate aldolase; Fructose-Bisphosphate Aldolase - metabolism; Glycolysis; Medical sciences; Models, Molecular; Myosin-Light-Chain Kinase - metabolism; Pharmacology. Drug treatments; Phosphofructokinase-1 - metabolism; Phosphoric Diester Hydrolases - metabolism; Trifluoperazine - pharmacology; Neuroleptic; Coronary vasodilator agent; Fluorescence; Molecular interaction; Substrate enzyme complex; In vitro; Glycolytic enzyme; Binding protein; Antagonism; Enzymatic activity; Investigation method; Anisotropy; Test; Antiarrhythmia agent; Calmodulin
• ISSN: 0026-895X; 1521-0111

A simple procedure has been elaborated to screen for the calmodulin antagonist effect of drugs. A covalently attached fluorescent probe was used to monitor the binding of enzymes known as target enzymes to calmodulin. Moreover, the probe made it possible to recognize a new target enzyme, aldolase (D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase, EC 4.1.2.13), for calmodulin among glycolytic enzymes. The calmodulin antagonist trifluoperazine prevented or eliminated the complex formation between calmodulin and enzymes studied in reconstituted systems; the Ca channel blockers had no effect. The functional consequences of the effect of drugs on calmodulin-phosphofructokinase (ATP:D-fructose-6-phosphate 1-phosphotransferase, EC 2.7.1.11) interaction were investigated as well. Whereas trifluoperazine suspended the calmodulin-mediated hysteretic inactivation of phosphofructokinase, Ca channel blockers (verapamil and nifedipine) were ineffective. Fendiline (regarded as a Ca channel blocker) seems to act as a functional calmodulin antagonist. Its binding to calmodulin does not prevent the complex formation of phosphofructokinase and calmodulin, but within this ternary complex phosphofructokinase preserves or recovers its original activity measured in the absence of calmodulin. The possible molecular effect of drugs on a calmodulin-enzyme complex is discussed.